1. Field of the Invention
The present invention relates to a fuel injection control device for an internal combustion engine.
2. Description of the Prior Art
FIG. 5 is a block diagram showing a typical conventional fuel injection control device for an internal combustion engine,
In the figure, reference numeral 1 denotes a control section which consists of a waveform shaping circuit 1-1 for shaping the outputs of various input sensors, a calculation section 1-2 for controlling fuel and ignition, an injector drive circuit 1-3 for driving injectors, and an ignition drive circuit 1-4 for driving ignition, Reference numeral 2 denotes a cam angle sensor for detecting phase angle position of the cam shaft, reference numeral 3 denotes a crank angle sensor for detecting angle reference position of cranks, reference numeral 4 denotes various sensors for detecting operating conditions, reference numerals 5 and 6 denote fuel injectors for respective cylinders, and reference numerals 7 and 8 denote ignition coils.
Now the operation of the fuel injection control device will be described with reference to FIGS. 6 and 7.
FIG. 6 is an operation timing chart of a conventional fuel injection control device for an internal combustion engine.
In FIG. 6, for example, an output signal S1 from the can angle sensor 2 and an output signal S2 from the crank angle sensor 3 are shaped by the waveform shaping circuit 1-1 and supplied to the calculation section 1-2. Then quantities of fuel for the injectors 5 and 6 are calculated by a fuel quantity calculation section 1-2a and ignition timings of the ignition coils 7 and 8 are calculated by an ignition timing calculation section 1-2b. The calculation results of fuel quantities are supplied to the injectors 5 and 6 as drive signals S3 and S4, respectively, via the injector drive circuit 1-3. The calculation results of ignition timings are supplied to the ignition coils 7 and 8 as drive signals S5 and S6, respectively, via the ignition drive circuit 1-4.
FIG. 7 is a control flowchart of the conventional fuel injection control device for an internal combustion engine.
In Steps ST1 to ST3, the period of revolution of the engine is calculated. Based on the calculation results, the base quantity of fuel is calculated in Step ST4. Next, in Step ST5, it is checked whether a cam angle signal was input during a crank angle interruption. If it was, fuel injection quantity INJ2 (injector 6) is determined (Step ST6). If no cam angle signal was input, fuel injection quantity INJ1 (injector 5) is determined (Step ST7). The injector drive is turned on (Step ST8), and finally the time of the current interruption of the crank angle is memorized (Step ST9). Then the process returns to the beginning.
Conventional fuel injection control devices for internal combustion engines, which are configured as described above, have the following problems.
With the conventional fuel injection control devices for internal combustion engines, if the fuel injection quantity during acceleration is controlled for each cylinder, it is difficult for all the fuel injected this time to enter the cylinders because of a time delay before the fuel injected by injectors reaches the cylinders through suction valves. Consequently, the air-fuel ratio of the current air-fuel mixture becomes lean to the extent that fuel remains upstream of the suction valves. This reduces the torque delivered by the engine. On the other hand, the air-fuel ratio of the next air-fuel mixture becomes richer by the amount of the extra air-fuel mixture which remained upstream of the suction valves. This extremely increases or decreases the torque delivered by the engine. The increases and decreases in the torque delivered by the engine increases car body vibrations and shocks, making it difficult to control the fuel injection quantity during transitional periods.
The present invention has been made to solve the above problems. Its object is to provide a fuel injection control device for an internal combustion engine which can control fuel injection quantities easily and simply by regulating them in such a way as to suppress car body vibrations and shocks.
A fuel injection control device for an internal combustion engine set forth in claim 1 of the invention comprises angle detection means for detecting one angle reference position of at least the suction stroke or earlier strokes of two cylinders whose strokes shift from each other by 360 degrees of crank angle in a four-cycle multi-cylinder engine; operating condition detection means for detecting the operating conditions of the engine; and fuel injection control means for determining the appropriate fuel injection quantity for each cylinder of the engine based on engine revolution information derived from the detected cycle of angle reference position detection signals obtained by the above described angle detection means and on operating condition detection signals obtained by the above described operating condition detection means, wherein xc2xd of the fuel injection quantity determined based on the engine revolution information derived from the detected cycle of the angle reference position detection signals of one of the above described two cylinders and on the above described operating condition detection signals is injected simultaneously into the above described two cylinders, and xc2xd of the fuel injection quantity determined based on the engine revolution information derived from the detected cycle of the angle reference position detection signals of the other of the above described two cylinders and on the above described operating condition detection signals is injected simultaneously into the above described two cylinders.
A fuel injection control device for an internal combustion engine set forth in claim 2 of the invention comprises angle detection means fitted in the crank shaft of a four-cycle multi-cylinder engine and detecting angle reference position of the engine; specific-cylinder detection means fitted in the cam shaft of the above described internal combustion engine and recognizing specific cylinders of the engine; operating condition detection means for detecting the operating conditions of the engine; and fuel injection control means for determining the appropriate fuel injection quantity for each cylinder of the engine based on engine revolution information derived from the detected cycle of angle reference position detection signals obtained by the above described angle detection means and on operating condition detection signals obtained by the above described operating condition detection means, wherein a particular proportion of the fuel injection quantity determined based on the engine revolution information derived from the detected cycle of the angle reference position detection signals from the above described angle detection means and on the above described operating condition detection signals is divided into multiple injections, based on recognition information obtained by the above described specific-cylinder detection means.
A fuel injection control device for an internal combustion engine set forth in claim 3 of the invention is the fuel injection control device according to claim 2, wherein the number of divisions of the fuel injection quantity determined based on the engine revolution information derived from the detected cycle of the angle reference position detection signals from the above described angle detection means and on the operating condition detection signals is changed according to the operating conditions of the engine.
A fuel injection control device for an internal combustion engine set forth in claim 4 of the invention is the fuel injection control device according to claim 2, wherein the particular proportion of the fuel injection quantity determined based on the engine revolution information derived from the detected cycle of the angle reference position detection signals from the above described angle detection means and on the operating condition detection signals is changed according to the operating conditions of the engine.
A fuel injection control device for an internal combustion engine set forth in claim 5 of the invention is the fuel injection control device according to claim 4, wherein the operating conditions of the engine which determine the above described particular proportion of the fuel injection quantity is changed according to at least engine speed.
A fuel injection control device for an internal combustion engine set forth in claim 6 of the invention is the fuel injection control device according to claim 4, wherein the operating conditions of the engine which determine the above described particular proportion of the fuel injection quantity is changed according to at least the temporal variation in engine speed.
A fuel injection control device for an internal combustion engine set forth in claim 7 of the invention is the fuel injection control device according to claim 4, wherein the operating conditions of the engine which determine the above described particular proportion of the fuel injection quantity is changed according to at least temperature information.
A fuel injection control device for an internal combustion engine set forth in claim 8 of the invention is the fuel injection control device according to claim 4, wherein the operating conditions of the engine which determine the above described particular proportion of the fuel injection quantity is changed according to at least the position of the transmission gear of the engine,
A fuel injection control device for an internal combustion engine set forth in claim 9 of the invention is the fuel injection control device according to claim 4, wherein the operating conditions of the engine which determine the above described particular proportion of the fuel injection quantity is changed according to at least the throttle opening of the engine.
A fuel injection control device for an internal combustion engine set forth in claim 10 of the invention is the fuel injection control device according to claim 4, wherein the operating conditions of the engine which determine the above described particular proportion of the fuel injection quantity is changed according to at least temporal variation in the throttle opening of the engine.
A fuel injection control device for an internal combustion engine set forth in claim 11 of the invention is the fuel injection control device according to any of claims 2 to 10, wherein the above described multiple split injections are mainly carried out at least at a point just after the end of the suction stroke and at a point just before the start of the suction stroke.